Small cell initial access and physical cell identity determination

Abstract

A method, system, and computer program product that provides a two-index system for clusters of small cells in a wireless network. A first index is employed for access to and identification of a serving cell within a cluster of small cells. A second index indicates a group of small cells for determining mobility control. The first index may be derived from primary/secondary synchronization signals, or from frequency/time division multiplex signal position. The second index may be indicated in system/master information block signals or predefined as a plurality of small cells identified by the first index for each cell. Determination of physical cell identification is aided by providing a plurality of primary/secondary synchronization (PSS/SSS) signal alternating configurations with indicator, wherein a maximum number of configurations is predefined. Signaling the PSS/SSS configurations by one of broadcast or dedicated signaling, said signaling indicating whether each configuration is one of periodic or aperiodic alternation.

What is claimed is: 
     
       1. A method comprising:
 providing a multiple-index system for clusters of small cells in a wireless cellular network, wherein 
 at least a first index is employed for access to and identification of an individual serving cell within a cluster of small cells, and 
 at least a second index is employed to indicate a group of small cells for determining mobility control, wherein the indicated group of small cells is configured to allow movement of a user equipment (UE) between a first small cell and a second small cell from the group of small cells, without triggering cell reselection or handover. 
 
     
     
       2. The method of  claim 1 , further comprising:
 indicating the first index through primary synchronization/secondary synchronization (PSS/SSS) signals. 
 
     
     
       3. The method of  claim 1 , further comprising:
 indicating the first index through at least a position of a PSS/SSS signal and/or a relative position between PSS and SSS. 
 
     
     
       4. The method of  claim 1 , further comprising:
 indicating the second index through system information/master information block signals. 
 
     
     
       5. The method of  claim 1 , further comprising:
 predefining the second index as comprising a plurality of small cells identified by the first index for each small cell. 
 
     
     
       6. The method of  claim 1 , further comprising:
 indicating the second index through primary/secondary synchronization (PSS/SSS) signals. 
 
     
     
       7. The method of  claim 1 , further comprising:
 causing an indication to be communicated in downlink signaling that the small cells comprise a multiple-index cell system. 
 
     
     
       8. The method of  claim 1  further comprising:
 defining a plurality of primary/secondary synchronization (PSS/SSS) signal configurations, each having an indicator, wherein 
 each configuration has a different relative time/frequency position of PSS and SSS signals. 
 
     
     
       9. An apparatus comprising at least one processor, a digital memory associated with the at least one processor, said memory storing computer code instructions which, when executed by the at least one processor, cause the apparatus to perform:
 providing a multiple-index system for clusters of small cells in a wireless cellular network, wherein 
 at least a first index is employed for access to and identification of an individual serving cell within a cluster of small cells, and 
 at least a second index is employed to indicate a group of small cells for determining mobility control, wherein the indicated group of small cells is configured to allow movement of a user equipment (UE) between a first small cell and a second small cell from the group of small cells, without triggering cell reselection or handover. 
 
     
     
       10. The apparatus of  claim 9 , further comprising instructions that cause the apparatus to perform:
 indicating the first index through primary synchronization/secondary synchronization (PSS/SSS) signals. 
 
     
     
       11. The apparatus of  claim 10 , further comprising instructions that cause the apparatus to perform:
 indicating the second index through system information/master information block signals. 
 
     
     
       12. The apparatus of  claim 10 , further comprising instructions that cause the apparatus to perform:
 predefining the second index as comprising a plurality of small cells identified by the first index for each small cell. 
 
     
     
       13. The apparatus of  claim 10 , further comprising instructions that cause the apparatus to perform:
 indicating the second index through primary/secondary synchronization (PSS/SSS) signals. 
 
     
     
       14. The apparatus of  claim 9 , further comprising instructions that cause the apparatus to perform:
 indicating the first index through at least a position of a PSS/SSS signal and/or a relative position between PSS and SSS. 
 
     
     
       15. The apparatus of  claim 9 , further comprising instructions that cause the apparatus to perform:
 causing an indication to be communicated in downlink signaling that the small cells comprise a two-index cell system. 
 
     
     
       16. The apparatus of  claim 9 , further comprising instructions that cause the apparatus to perform:
 defining a plurality of primary/secondary synchronization (PSS/SSS) signal configurations, each having an indicator, wherein 
 each configuration has a different relative time/frequency position of PSS and SSS signals. 
 
     
     
       17. The apparatus of  claim 16 , wherein
 the time/frequency for each defined signal configuration of PSS/SSS is orthogonal to each other. 
 
     
     
       18. An apparatus comprising at least one processor, a digital memory associated with
 the at least one processor, said memory storing computer code instructions which, when executed by the at least one processor, cause the apparatus to perform:
 receiving an indication that one or more of a cluster of small cells uses a multiple-index system for access to said and control of said small cells in a wireless cellular network, wherein 
 at least a first index is employed for access to and identification of an individual serving cell within a cluster of small cells, and 
 at least a second index is employed to indicate a group of small cells for determining mobility control, wherein the indicated group of small cells is configured to allow movement of a user equipment (UE) between a first small cell and a second small cell from the group of small cells, without triggering cell reselection or handover. 
 
 
     
     
       19. The apparatus of  claim 18 , further comprising instructions that cause the apparatus to perform:
 deriving the first index from primary synchronization/secondary synchronization (PSS/SSS) signals. 
 
     
     
       20. The apparatus of  claim 18 , further comprising instructions that cause the apparatus to perform:
 deriving the first index through at least a position of a PSS/SSS signal and/or a relative position between PSS and SSS.